patella Flashcards
Where is the apex of the patella?
inferior
Which surface of patella is larger?
lateral articular facet is larger than medial
Where does the quads tendon insert on the patella?
superior surface
What does the patellar ligament connect?
apex to tibial tuberosity
what does the patella maintain from the tibia during flexion and extension?
distance above tibia during flexion and extensio
What does the the patella ligament does during extension and flexion?
keeps it from being pulled superiorly, so it travels inferiorly on the femur during knee flexion.
What is the ballot able patella sign?
Rebounding of depressed patella indicates knee effusion: the patella is ballotable
Why is th epatella ballot able in a ballotable patella sign?
because it is floating on a pool of fluid instead of being in contact with the femur
What does the patella do?
acts to magnify the excursion of the leg, at the expense of power
How doe th patella pull down on the tibia?
with less force than the quadriceps muscle pulls on the patella
Therefore the extending leg swings faster and through a larger arc, but this requires more energy.
What can patella fractures result from?
impacts to the knee, or sudden powerful contraction of the quadriceps
What is the fabella?
In 3-5% of people, the lateral head of the gastrocnemius contains a sesamoid bone,
When does the patella ossifies?
at 3 to 6 years of age. from more than on ossification center
What is a bipartite patella?
when the patella doesn’t fuse into one
How can a bipartite patella be distinguished from a patella fracture?
fusion defects are usually present bilaterally.
a patellar fracture, tension from the quadriceps MM will often pull the two pieces apart; the pieces of a bipartite patella will normally have a seam between them but not a gap.
What is the knee jerk response?
Used to test innervation of the quadriceps
how is a knee jerk response performed ?
A firm strike on the patellar ligament with a reflex hammer activates muscle spindles in the quads. Afferent impulses from the spindles travel in the femoral N to the L2-L4 segments of the spinal cord.
The reflex arc is completed by efferent impulses transmitted by motor fibers of the femoral N to the quads, producing:
What is a visible sign of the knee jerk response?
sudden, jerk-like contraction of the quads extension of the leg at the knee (visible sign)
